diff --git a/release_notes.md b/release_notes.md
index b123c479ca..3ff0177864 100644
--- a/release_notes.md
+++ b/release_notes.md
@@ -1,6 +1,7 @@
-### Release notes
-
-<!-- Please add your release notes in the following format:
-- My change description (#PR)
--->
-- Memory allocation optimizations in `ScriptStartupTypeLocator.GetExtensionsStartupTypesAsync` (#11012)
+### Release notes
+
+<!-- Please add your release notes in the following format:
+- My change description (#PR)
+-->
+- Memory allocation optimizations in `ScriptStartupTypeLocator.GetExtensionsStartupTypesAsync` (#11012)
+- Fix invocation timeout when incoming request contains "x-ms-invocation-id" header (#10980)
diff --git a/src/WebJobs.Script.Grpc/Properties/AssemblyInfo.cs b/src/WebJobs.Script.Grpc/Properties/AssemblyInfo.cs
index e3874ae556..6c2d8837b2 100644
--- a/src/WebJobs.Script.Grpc/Properties/AssemblyInfo.cs
+++ b/src/WebJobs.Script.Grpc/Properties/AssemblyInfo.cs
@@ -5,4 +5,5 @@
 
 [assembly: InternalsVisibleTo("Microsoft.Azure.WebJobs.Script.Benchmarks")]
 [assembly: InternalsVisibleTo("Microsoft.Azure.WebJobs.Script.Tests")]
-[assembly: InternalsVisibleTo("Microsoft.Azure.WebJobs.Script.Tests.Integration")]
\ No newline at end of file
+[assembly: InternalsVisibleTo("Microsoft.Azure.WebJobs.Script.Tests.Integration")]
+[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2")]
\ No newline at end of file
diff --git a/src/WebJobs.Script.Grpc/Server/DefaultHttpProxyService.cs b/src/WebJobs.Script.Grpc/Server/DefaultHttpProxyService.cs
index 235bbee981..1d164c2c04 100644
--- a/src/WebJobs.Script.Grpc/Server/DefaultHttpProxyService.cs
+++ b/src/WebJobs.Script.Grpc/Server/DefaultHttpProxyService.cs
@@ -2,7 +2,6 @@
 // Licensed under the MIT License. See License.txt in the project root for license information.
 
 using System;
-using System.Collections.Generic;
 using System.Linq;
 using System.Net.Http;
 using System.Threading.Tasks;
@@ -96,8 +95,8 @@ public void StartForwarding(ScriptInvocationContext context, Uri httpUri)
             HttpContext httpContext = httpRequest.HttpContext;
             httpContext.Items[ScriptConstants.HttpProxyingEnabled] = bool.TrueString;
 
-            // add invocation id as correlation id
-            httpRequest.Headers.TryAdd(ScriptConstants.HttpProxyCorrelationHeader, context.ExecutionContext.InvocationId.ToString());
+            // add invocation id as correlation id, override existing header if present
+            httpRequest.Headers[ScriptConstants.HttpProxyCorrelationHeader] = context.ExecutionContext.InvocationId.ToString();
 
             var forwardingTask = _httpForwarder.SendAsync(httpContext, httpUri.ToString(), _messageInvoker, _forwarderRequestConfig).AsTask();
             context.Properties[ScriptConstants.HttpProxyTask] = forwardingTask;
diff --git a/test/WebJobs.Script.Tests/HttpProxyService/DefaultHttpProxyServiceTests.cs b/test/WebJobs.Script.Tests/HttpProxyService/DefaultHttpProxyServiceTests.cs
new file mode 100644
index 0000000000..3356ed2017
--- /dev/null
+++ b/test/WebJobs.Script.Tests/HttpProxyService/DefaultHttpProxyServiceTests.cs
@@ -0,0 +1,82 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the MIT License. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Microsoft.AspNetCore.Http;
+using Microsoft.Azure.WebJobs.Script.Description;
+using Microsoft.Azure.WebJobs.Script.Grpc;
+using Microsoft.Extensions.Logging;
+using Moq;
+using Xunit;
+using Yarp.ReverseProxy.Forwarder;
+
+namespace Microsoft.Azure.WebJobs.Script.Tests
+{
+    public class DefaultHttpProxyServiceTests
+    {
+        private readonly Mock<IHttpForwarder> _httpForwarderMock;
+        private readonly Mock<ILogger<DefaultHttpProxyService>> _loggerMock;
+        private readonly DefaultHttpProxyService _proxyService;
+
+        public DefaultHttpProxyServiceTests()
+        {
+            _httpForwarderMock = new Mock<IHttpForwarder>();
+            _loggerMock = new Mock<ILogger<DefaultHttpProxyService>>();
+            _proxyService = new DefaultHttpProxyService(_httpForwarderMock.Object, _loggerMock.Object);
+        }
+
+        [Fact]
+        public void StartForwarding_SetsCorrelationHeader()
+        {
+            var httpContext = new DefaultHttpContext();
+            httpContext.Items.Add(ScriptConstants.AzureFunctionsHttpTriggerContext, new());
+            var invocationId = Guid.NewGuid();
+            var context = new ScriptInvocationContext
+            {
+                FunctionMetadata = new FunctionMetadata { Name = "TestFunction" },
+                ExecutionContext = new ExecutionContext { InvocationId = invocationId },
+                Inputs = new List<(string Name, DataType Type, object Val)>
+                {
+                    ("req", DataType.String, httpContext.Request)
+                },
+                Properties = new Dictionary<string, object>()
+            };
+
+            var httpUri = new Uri("http://localhost");
+
+            _proxyService.StartForwarding(context, httpUri);
+
+            var httpRequest = (HttpRequest)context.Inputs.First().Val;
+            Assert.True(httpRequest.Headers.ContainsKey(ScriptConstants.HttpProxyCorrelationHeader));
+            Assert.Equal(invocationId.ToString(), httpRequest.Headers[ScriptConstants.HttpProxyCorrelationHeader]);
+        }
+
+        [Fact]
+        public void StartForwarding_OverridesExistingCorrelationHeader()
+        {
+            var httpContext = new DefaultHttpContext();
+            httpContext.Items.Add(ScriptConstants.AzureFunctionsHttpTriggerContext, new());
+            var invocationId = Guid.NewGuid();
+            var context = new ScriptInvocationContext
+            {
+                FunctionMetadata = new FunctionMetadata { Name = "TestFunction" },
+                ExecutionContext = new ExecutionContext { InvocationId = invocationId },
+                Inputs = new List<(string Name, DataType Type, object Val)>
+                {
+                    ("req", DataType.String, httpContext.Request)
+                },
+                Properties = new Dictionary<string, object>()
+            };
+
+            var httpUri = new Uri("http://localhost");
+            var existingCorrelationId = Guid.NewGuid().ToString();
+            var httpRequest = (HttpRequest)context.Inputs.First().Val;
+            httpRequest.Headers[ScriptConstants.HttpProxyCorrelationHeader] = existingCorrelationId;
+
+            _proxyService.StartForwarding(context, httpUri);
+            Assert.Equal(invocationId.ToString(), httpRequest.Headers[ScriptConstants.HttpProxyCorrelationHeader]);
+        }
+    }
+}
\ No newline at end of file